cocaine Flashcards
what it cocaine derived from?
coca plant
what was cocaine used for in the past?
herbal remedy
who was the psychologist that was greatly enthused by cocaine and its beneficial side effects?
Sigmund Freud
where does the coca plant originate from?
South America
traditionally, who and how was the coca plant used?
- Bolivian minors
- chewed coca leaf
- helped them work long hours
- this is because cocaine is a stimulant (just like coffee and nicotine)
give examples of how cocaine was previously used
- chewing coca leaf
- local anaesthetic for teething babies
- cocktail drinks
- active ingredient of coca-cola in early 1900’s
identify properties and uses of cocaine
- water soluble
- water soluble in form of hydrochloride salt
- crack = freebase and suitable for smoking
how is the most rapid and highest peak from cocaine produced?
- produced by intravenous administration (injection)
what effect does smoking freebase cocaine result in?
- rapid peak
- less pronounced than if you were in inject
what effect does snorting/intranasal administration of cocaine have?
- later peak
- higher peak than smoking
what effect does oral administration of cocaine have?
- most delayed onset of effects
identify behavioural effects of cocaine in humans
mild/moderate (typically positive)
- euphoria
- increased interest in sex/inflated self-esteem
- heightened energy
- heightened excitement
severe (typically negative)
- irritability
- hostility
- anxiety
- fear
- exhaustion
- rambling
delusions of grandiosity
what does the hypothetical relationship between cocaine use, dopamine levels and mood resemble?
a sine wave
- initially increased synaptic concentrations of dopamine = associated with euphoria
- followed by reduced synaptic concentration of dopamine = associated with craving and dysphoria (negative mood)
how are cocaine’s effects mediated?
- mediated by its actions on the sympathetic nervous system
- SNS = speeds up processes
- increases alertness
- increases heart rate
- increases blood flow to muscles
what are some physiological effects of cocaine?
- high and ‘rush’
- vasoconstriction (contraction of blood vessels -> increasing blood pressure)
- hypertension (abnormally high blood pressure)
- stroke
- intercranial haemorrhage
describe the mechanisms of cocaine action
- dopamine travels down axon enclosed in vesicles
- vesicles merge with pre-synaptic membrane
- dopamine released
- level of post-synaptic activation depends on availability of dopamine within synaptic cleft
- this is regulated by dopamine transporter
- this normally removes excess dopamine for re-use
- cocaine blocks dopamine transporter
- causes dopamine availability within synaptic cleft to increase
- causes post-synaptic activity of dopamine neurones to increase
other than dopamine receptors, what else does cocaine block?
- inhibits synaptic levels of noradrenaline
- inhibits serotonin
- blocks nerve conduction by inhibition of sodium channels
what compound has been used in clinical trials as a treatment for cocaine relapse and craving?
- lidocaine
explain the role of dopamine in psychomotor stimulant-induced behaviour (with regards to brain areas)
- dopamine projections from nucleus accumbens and striatum
- these areas are mostly where dopamine is produced
- most extreme purely motor effect = stereotypy (persistent repetition of an act with no meaning)
- stereotypy = identified with the striatum
what neurotransmitter is they key to the understanding of the mechanisms of cocaine action? give examples
- dopamine
- microinjections of cocaine into nucleus accumbens = increase locomotor activity
- tests of self-administration to nucleus accumbens test for localised reinforcing effects
- lesions to nucleus accumbens deplete dopamine, reducing locomotor activity and the reinforcing effects of cocaine (reinforcing effects = increasing levels of dopamine)
outline Rocha et al. (1998) study into cocaine self-administration in individual wild-type mice
- collected data for 4 mice
- looking at the importance of dopamine transporter (DAT)
- in mice lacking dopamine transporter, it was found that self-administering of cocaine decreased
- highlighting importance of cocaines actions at dopamine transporter
- wild-type mice without genetic deletion = found steady increase in total number of injections
- confirms role of dopamine transporter and the reinforcing effects of cocaine
outline Vorel et al. (2002) study that looks into cocaines enhancement of brain stimulation reward by a dopamine antagonist
- cocaine normally adds to the effects of brain stimulation reward (BSR)
- implanted stimulating electrodes in part of reward pathway
- cocaine enhanced rats responded for BSR = 20% over baseline
- cocaines enhancement of BSR = blocked by SB-277011-A (dopamine antagonist)
- appeared to decreased enhancement of BSR
outline Inada et al. (1992) study into how cocaine’s actions depend on the schedule of administration
- measured locomotor activity in 3 groups
- saline infused rats = control group
- cocaine infused group were first administered cocaine over 11 days
- then cocaine challenge was produced by an injection of cocaine
- locomotor activity in response to cocaine challenge shows evidence that chronic pre-treatment with continuous infusion produced tolerance
- shows schedule of administration produced a tolerance
outline Post & Contel (1983) study into chronic use of cocaine and how it can lead to sensitisation rather than tolerance
- researchers administered cocaine as single injection per day
- behavioural measure = stereotypy ratings
- increasing stereotypy levels were shown over the successive days of the study and cocaine treatments
- because stereotypy was increased -> suggests that sensitisation was induced
- sensitisation = increased responsitivity
what does the development of tolerance depend on?
administration schedule
- behavioural response measured
- time elapsed since last dose
- short time since last dose = associated with tolerance
- long time since last dose = associated with sensitisation
identify pharmacological treatments for cocaine addiction
- use of antidepressants = modulates dopamine indirectly
- dopamine antagonists
- vaccines
identify behavioural treatments for cocaine addiction
- avoiding triggers for relapse
identify psychosocial treatments for cocaine addiction
- counselling
- support
outline Carreza et al. (2001) study into behavioural responses to cocaine in vaccinated rats
- measures activity between immunised and non-immunised rats following the challenge of a cocaine injection
- cocaine = expected to produce surge in activity
- found that surge in activity = greatly reduced in immunised group
- shows that behavioural and physiological responses to cocaine should be similarly reduced by vaccines
